Oakland wrapped up its seven-game road trip with a 6-1 record, its best stint away from home in six years.
"After losing the first game, we won every one," Melvin said. "It has to be one of the more successful road trips we've had in a while."
The latest win was a collective effort.
The A's have been lauded for their pitching in recent weeks. Oakland entered Thursday's tilt with a 2.41 ERA over an 11-2 stretch. On this sunny August afternoon, however, the A's bats propelled them to victory.
Playing for the first time in the series, Kottaras roped a three-run double to center field to break a 1-1 tie in the fourth.
"George put a good swing on a little ball that was down and away," said Indians starter Justin Masterson, who the A's tagged for eight runs in four innings. "I thought it was a pretty good pitch. They got three runs there, and then they scored more runs."
Melvin appreciated Kottaras' ability to shake off the rust and deliver.
"That was a key hit at the time to get us off to where we had somewhat of a lead," Melvin said. "We feel good about him. He doesn't get to play all that much, but we feel he's a good tandem with [Derek Norris]."
Pennington entered the contest batting just .194 this season, including .138 (8-for-58) over his previous 19 games. He plated Kottaras with a two-run homer that barely cleared the right-field fence.
"Penny gave us some good production today," Melvin said. "It was a good day for him. We need to be able to have production up and down the order. We're not just going to dominate in one area."
For the second straight day, the A's benefited from a bounty of hits from all over their batting order. Eight A's starters contributed at least one hit, including right fielder Josh Reddick, who tallied three to give him nine for the series. Over his last five games, Reddick is batting .522 (12-for-23).
"It's been that way all year," Reddick said. "We haven't just been relying on one guy every night. It's been one through nine every day."
The A's didn't get complacent. Melvin noted after Wednesday's 8-4 win how his offense has improved at tacking on insurance runs late in games. They continued that trend on Thursday, even as Cleveland clawed its way back.
In the fifth, Reddick socked a two-run homer. An inning later, Oakland pushed its lead to 10-3 following a sacrifice fly by shortstop Stephen Drew and an RBI single from Reddick.
When the Indians struck for three runs in the bottom of the sixth, knocking starter Jarrod Parker out of the game, the A's answered right back with their 11th run. In the ninth, third baseman Josh Donaldson connected on his second homer in 24 hours to complete the scoring.
Parker departed without recording an out in the sixth. He surrendered five runs on eight hits, yet still earned his ninth victory.
"It was important that we kept scoring," Melvin said. "It felt like it was a hitter's day. Every pitcher had some trouble out there."
The A's have now won six in a row, eight of nine and 12 of 14. For the first time since the conclusion of the 2006 campaign, the A's are more than 15 games over .500.
Everyone on the roster has chipped in to the cause, and the A's are loving every minute of it.
"No one expected us to do anything," Reddick said. "Obviously we're opening a lot of eyes and surprising a lot of people, and that's what we enjoy."